1 Houston Advanced Research Center, The Woodlands, and University of Texas, Austin, United States2 Department of Atmospheric Sciences, Texas A&M University, College Station, United States3 Center for Research in Water Resources, University of Texas, Austin, United States

Engineered rivers in arid lands play an important role in feeding the world’s growing
population. Each continent has rivers that carry water from distant mountain sources to
fertile soil downstream where rainfall is scarce. Over the course of the last century most
rivers in arid lands have been equipped with large engineering structures that generate
electric power and store water for agriculture and cities. This has changed the hydrology
of the rivers. In this paper we discuss how climate variation, climate change, reservoir
siltation, changes in land use and population growth will challenge the sustainability of
engineered river systems over the course of the next few decades. We use the Rio Grande
in North America, where we have worked with Mexican and American colleagues, to
describe our methodology and results. Similar work is needed to study future water
supply and demand in engineered rivers around the world.